The spinal column is comprised of twenty-six interlocking vertebrae. These vertebrae are separated by discs. The spine provides load bearing support for one-half of the body's mass and it protects the nerves of the spinal column. The discs provide shock absorption and facilitate the bending of the spine.
The combination of the vertebrae and discs at each vertebral segment allows for motion of the spine, in particular, flexing, rotation, and extension. The motion and support functions of the spine, in combination with the many interlocking parts and nerve roots associated with the spinal column can result in back pain due to various reasons. Such back pain may result from the degeneration of discs due to age, disease, or injury. Further, vertebral bodies may be compromised due to disease or defect, such as a tumor, or injury, such as a fracture. In certain cases, it becomes necessary to remove or replace one or more of the vertebral bodies or discs to alleviate pain or regain spinal functionality.
Spinal fusion or lumbar spinal fusion is one way to treat a compromised vertebral body due to unstable burst fractures, severe compression fractures, and tumor decompression. In a spinal fusion procedure, the discs above and below the compromised vertebral body are removed and a strut graft and plate are then used to make the vertebrae above and below the replaced vertebral body grow together and become one bone. More surgery may be necessitated in the future as the adjacent spine wears out. The function of a fused spine is usually diminished compared to a normal spine because the flexibility of the fused segments is removed. Because the intention of a spinal fusion procedure is to create solid bone in the area that is excised, the spacer that is inserted to restore normal height may be configured to enhance bone in-growth, which may be enhanced by the addition of bone growth material.
Pedicle screws are becoming more common in spine surgery because of their use in stabilizing the spine. The pedicle is a strong point of attachment in the spine, so pedicle screws may be attached between a vertebral prosthesis and the adjacent pedicle to fix the prosthesis in place. Screws are inserted through the cancellous bone of the pedicle into the vertebral prosthesis.
There is a need for a vertebral prosthesis that is configured to be used in conjunction with artificial disc replacements above and below the replaced vertebra, thus preserving the motion and stability of the vertebral segment by obviating the need for a spinal fusion procedure. Further, there is a need for a vertebral prosthesis that may be used with or without a spinal fusion procedure to provide flexibility to the surgeon performing the vertebral replacement surgery. Further still, there is a need for a vertebral prosthesis that is configured to be used in conjunction with artificial discs having different configurations in order to provide procedural flexibility. Further still, there is a need for a vertebral prosthesis that is configured to be used with or without pedicle screws.
It would be desirable to provide a system and/or procedure that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.